This invention relates to building blocks and in particular building blocks formed with mating tongue in grooves along their adjacent edges.
It has been a problem with tongue in groove blocks that while the tongue in groove provide for longitudinal alignment of the blocks during their laying, when the blocks are laid one upon the other the loading between the blocks is accommodated by the bonding composition between the blocks and while that bonding composition is setting the vertical alignment of the blocks can vary.
It is an object of this invention to provide building blocks whereby on the blocks being laid they are positively supported by each other to prevent any misalignment while the bonding composition between the blocks sets.